1. Field of the Invention
The present invention relates in general to a method and device for producing a special effect and, more specifically, to a method of producing an illusion of thickness from a flat image viewable with the unaided eye and a device for producing an animated presentation viewable with the unaided eye having an illusion of thickness from the flat image.
2. Description of the Prior Art
Numerous methods and devices for creating an illusion of thickness have been provided in the prior art. For example, one such method and device known popularly as the "infinity mirror" may be used to create an illusion of thickness. This device includes a full mirror having a reflectance approaching 100%, and a partially silvered or transparent mirror having a reflectance of approximately 50% and a transparency as low as 8%. The two mirrors are positioned to extend substantially parallel and spaced from each other to form a gap therebetween. The reflective sides of the two mirrors are also positioned to face each other. When an observer views an illuminated display positioned between the two mirrors through the transparent mirror, an array of singular reflections is observed, separated by equal gaps, which recede and fade away from both the original image and the observer into the depth of the field of view.
In the case of the "infinity mirror", the traditional two mirror arrangement yields a maximum number of visible reflections possible for the type of material used, i.e. adding additional partially reflective surfaces decreases the number of visible reflections produced. This is evident from the graphical representation of FIG. 12. The relatively low transparency/reflectivity ratio of transparent mirrors leaves little light beyond the first reflection for distribution to other reflections thus reducing the ability to produce additional reflections.
Raising the transparency/reflectivity ratio of the mirrors by using glazing material or the equivalent, while increasing the number of sheets used, greatly increases the distribution of light to the increased number of surfaces, thereby generating a greater number of visible reflections. Each reflection in the resulting series of reflections is actually a composite, a superimposition of many singular reflections generated by each additional sheet in a complex way as is illustrated in the graphs of FIGS. 10 and 11. The number of highly visible composite reflections possible under normal viewing conditions, using commercially available lighting, is equal to or greater than the number of sheets used as can be seen from FIG. 12.
FIGS. 10 and 11 illustrate the pattern of incident light vectors of a single sheet screen and a 4 sheet screen, respectively. It can be seen from these figures that two different theoretically infinite series of reflections of the original image result, each reflection spaced at an interval equal to twice the thickness of the sheets in the screen. In the single sheet example shown in FIG. 10, each reflection position contains one reflection while, in the multiple sheet screen illustrated in FIG. 11, each position contains many reflections produced and distributed by each sheet in the screen and superimposed upon one another. This can be verified by tracing and counting the number of vector paths associated with each observer in FIGS. 10 and 11.
A determination of incident light values for each vector presented in the drawings may be made by expressing them in a simplified, idealized form. By ignoring the effects of distance and absorption, each vector can be assumed to be the sum of reflected and transmitted light from vectors immediately preceding them.
For example, the fraction of incident light in the vector labeled K4 in FIG. 11 may be assumed to equal to: EQU tK3+rJ4
wherein
tK3 is the light transmitted from the vector labeled K3; PA1 t=1-r wherein r is the reflectivity of the material; and PA1 rJ4 is the light reflected from the vector labeled J4.
The use of glazing material instead of mirrors provides nearly seamless illusion of depth created by closely spaced reflections. The "infinity mirror" configuration does not easily allow for close proximity between the two mirrors as the displayed object is usually placed between the mirrors. Although it is possible to create apertures or cutout portions in a full mirror to create a display, such is difficult, costly and, in terms of design creation, beyond the ability of most lay people. Therefore, in order to produce this device, multiple sheets of glazing material are required for use rather than partial mirrors.
While the described methods and devices may be suitable for the particular purpose to which they address, they would not be as suitable for the purposes of the present invention as heretofore described.